This application claims the benefit of Korean Application No. P2000-74288, filed in Korea on Dec. 7, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a flat type fluorescent lamp, and more particularly, to a flat type fluorescent lamp that is applicable to a backlight and a flat light source of a liquid crystal display (LCD) device.
2. Background of the Related Art
Recently, research of flat panel displays has been actively pursued. Especially, flat panel displays such as liquid crystal display (LCD) devices, field emission displays (FLD), electro luminescence displays (ELD), and a plasma display panels (PDP) have attracted considerable attention. Among the flat panel displays, which are unlike light-emitting flat panel displays, the LCD device does not emit light. Thus, a picture display cannot be viewed in the LCD device without a light.
In order to solve this problem, a separate light source, such as a backlight, is formed in a lower portion of a liquid crystal panel to uniformly irradiate light into a display panel. The back light assembly may be classified as either an edge light type or a direct type. In the direct type back light assembly, a fluorescent lamp is mounted in a lower portion of a liquid crystal panel, and a light-diffusion plate is mounted between the fluorescent lamp and the liquid crystal panel. In the edge light type back light assembly, light generated from the fluorescent lamp mounted at the side of the liquid crystal panel is distributed over the entire LCD screen using a transparent light-guiding plate. Recently, a flat type has been proposed that can uniformly irradiate light. In the flat type back light assembly, a phosphor layer is deposited on inner surfaces of the upper and lower substrates on opposing surfaces of the liquid crystal panel, and then electrodes are selectively mounted.
Large-sized display panels require a light source that irradiates uniform light. Flat type back light assemblies are best suited for this application.
A related art flat type fluorescent lamp is described below with reference to the accompanying drawings. Generally, as shown in FIG. 1, the flat type fluorescent lamp includes a reflecting portion 1, a light-emitting portion 2, and a light-diffusion portion 4. In an LCD device, the liquid crystal panel is formed above the light-diffusion portion 4. Herein, the reflecting portion 1 reflects light that is emitted away from the liquid crystal panel back toward the liquid crystal panel.
The light-diffusion portion 4 includes a light-scattering means for scattering the light preventing the reflecting portion 1 from reflecting the shape of a lamp onto the display panel. For example, the light may be very intense where the light-emitting portion of the lamp is located, while the remaining portions, situated away from the lamp, may be relatively dark. As a result, the shape of the lamp is reflected on the display panel. Accordingly, the light-scattering means is used to prevent the shape of the lamp from being reflected on the display panel, and to uniformly distribute a given quantity of light. The light-scattering means 5 includes one or more light-scattering medium layers. Sometimes a sheet is formed on the light-scattering means to enhance display quality and improve characteristic of light.
As the display area increases, the light-emitting area of the backlight also increases. In accordance to the increase in the light-emitting area, the thickness of the light-scattering means should also be increased to have a sufficient thickness to prevent the light-scattering means from subsiding. If the light-scattering means does not have a sufficient thickness, as shown in FIG. 2, the light-scattering means subsides, so that the quantity of light is unevenly distributed.
The light-emitting portion 2, which is unlike the related art direct type and the light-guiding plate type, includes a flat type lamp opposing the display panel of the liquid crystal panel. In the flat type, however, the entire light-emitting area is not equally bright. Actually, some portions of the light-emitting area are partially dark. The dark portions are caused by the following reasons. In the liquid crystal panel above the backlight, a spacer that maintains a constant distance between the upper and lower substrates cuts off a light path. In a flat luminescent lamp, a barrier that separates adjacent light-emitting paths from each other cuts off a light path. To obtain constant luminance on the entire light-emitting area, light-scattering medium layers have to be deposited while maintaining the predetermined distance from the light-emitting area.
In view of the related art, however, the flat type fluorescent lamp has several problems. As the size of the liquid crystal panel increases, deformation of the light-scattering means occurs, and the light path from the backlight is partially cut off, thereby unevenly distributing a quantity of light. Therefore, several light-scattering medium layers having the predetermined thickness are required to obtain a thick light-scattering means, and to thereby prevent light from being unevenly distributed.
In this case, however, the luminance is low and deformation of the light-scattering means is caused due to its weight. Also, friction between the light-scattering medium layers occurs. For this reason, foreign particles are generated, thereby increasing the manufacturing cost.
In view of the above problems, a flat type fluorescent lamp according to the present invention includes a plurality of supporters that may be provided between a light-emitting portion and a light-scattering portion to uniformly maintain the distance between them regardless of a thickness of the light-scattering means to thereby obtain high luminance, and uniformly distribute a quantity of light.
A flat type fluorescent lamp according to the present invention includes a first substrate, a second substrate, a light-emitting layer formed between the first and second substrates, a plurality of supporters selectively deposited on the first substrate, and a light-scattering means formed maintaining a predetermined distance from the first substrate by the supporters.
For example, the flat type fluorescent lamp according to the present invention may include a plurality of supporters that maintain the predetermined distance between the light-emitting portion and the light-scattering means on the light-emitting area, to obtain a thin light-scattering means without deformation and subsiding of the light-scattering means. Additionally, even if the light-scattering means is thickly formed, it is possible to prevent the light-scattering means from subsiding due to its weight.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.